Piranha Plant (SSBU)/Footstooled attack
Piranha Plant shoots out of its pot/pipe to bite any opponent that footstools it during its crouch animation. Due to the very specific and and uncommon situation of Piranha Plant being footstooled during its crouch animation, this move typically never gets seen. Its only notable use is for Joker's 'gun loops', as the combo is frame perfect to perform on Piranha Plant and requires a footstool to continue, in which Piranha Plant can buffer a crouch and perform the attack.
The move itself is bizarrely good, as it possesses a large, disjointed hitbox, extremely low endlag, and such low knockback to the point it won't kill until around 450% on midweights. It is an incredibly good combo starter and can lead to kill confirms on platforms. The move is also able to be used even during the start of Piranha Plant's crouch. Overall however, it is typically regarded as completely useless due to the unlikely scenario that it can only be used in. Due to its frame data, it is also possible for certain fast moves such as Incineroar's Revenge to beat it out. Additionally, any character can also buffer an airdodge out of it.